Hydrogen isotope retention and recycling in fusion reactor plasma-facing components

Micro and Nano Machining by Electro-Physical and Chemical Processes

The high-energy, high-intensity neutron fluxes produced by the fusion plasma will have a significant life-limiting impact on reactor components in both experimental and commercial fusion devices. As well as producing defects, the neutrons bombarding the materials initiate nuclear reactions, leading to transmutation of the elemental atoms. Products of many of these reactions are gases, particularly helium, which can cause swelling and embrittlement of materials.This paper integrates several different computational techniques to produce a comprehensive picture of the response of materials to neutron irradiation, enabling the assessment of structural integrity of components in a fusion power plant. Neutron-transport calculations for a model of the next-step fusion device DEMO reveal the variation in exposure conditions in different components of the vessel, while inventory calculations quantify the associated implications for transmutation and gas production. The helium production rates are then used, in conjunction with a simple model for He-induced grain-boundary embrittlement based on electronic-structure density functional theory calculations, to estimate the timescales for susceptibility to grain-boundary failure in different fusion-relevant materials. There is wide variation in the predicted grain-boundary-failure lifetimes as a function of both microstructure and chemical composition, with some conservative predictions indicating much less than the required lifetime for components in a fusion power plant.

https://www.iter.org/doc/www/content/com/Lists/Stories/Attachments/1384/NUCFUS.pdf

An integrated model for materials in a fusion power plant: transmutation, gas production, and helium embrittlement under neutron irradiation

Plant roots perform a myriad of functions right from the anchorage of plants to storage of reserve food material for the adverse weather. Roots forage around the soil for acquisition of ions and water and continually develop new branches. However, very little is known about the molecular mechanisms regulating root development and differentiation. We have endeavoured to decipher the genetic regulation of root formation in tomato by screening mutants defective in root development. We have isolated several mutants with altered morphology of roots. These mutants have been characterized for their phenotypes throughout the life cycle. In this report we show that for few of the mutants the vigour of plant is directly related to modification in the root structure. The potential utility of these mutants in understanding root development and also improving yield of tomato is discussed.

The International Atomic Energy Agency

https://hal.archives-ouvertes.fr/hal-00142084/document

B. A. Gurovich

Papers

Assessment of relative contributions from different mechanisms to radiation embrittlement of reactor pressure vessel steels

Intergranular and intragranular phosphorus segregation in Russian pressure vessel steels due to neutron irradiation

Comparison of microstructural features of radiation embrittlement of VVER-440 and VVER-1000 reactor pressure vessel steels

Thermal ageing mechanisms of VVER-1000 reactor pressure vessel steels

Radiation damage of graphite and carbon-graphite materials